He probably does have a small leak of gas that evaporates. He could check the filter area with the black cover off soon after driving or just tightened up the clamps to see if the long start goes away for a day or two. If there is a high pitch noise from rear while driving at high speeds it is definitely an air leak. But he could just keep changing the filter, not my car or money!

 

Screw clamps are best especially under pressure if properly sized and yes the fuel line is under pressure there is NO air going in, that would be a false story!.Slow starts are the delay getting pressure to the fuel pintels. Enjoy Woody

 

In the FWIW department, we do use Oetiker clamps, and have the factory tool for installation. Spring clamps are good, but note that OEM applications likely use ones that are two layers - double spring pressure. Screw clamps are fine, just don't work as well on small lines. Of course the Oetiker are single use, and the silly filter has four connections. Naturally, we use AN fittings on our race cars.

Just put the car on the lift to change the fuel filter with the OEM unit. Will see what this does.

 

Well, does not appear to be the fuel filter/pressure regulator.
A correction to my first post on this thread. It was not a WIX filter, but a made in Germany Mann Filter WK 720 that was installed to replace the Chrysler/MB original unit. The second replacement was a MB filter, number A 002 477 30 01 actually made in Germany. Installing the new filter made no difference in the cranking issue, therefore the check valve in the filter/regulator does not appear to be the problem. Oetiker clamps were again used.

I've attached pictures which are of the filter/regulator and hoses. On photo 2375, there is metal canister installed inline - this is outlined in a red circle. It is inline with the fuel line going from the filter/regulator to the fuel rail/engine. Any idea what this is?

Another attachment, labeled fuel system schematic, is from page 14-2 (volume 2 of 3) of the factory shop manual. Note that this schematic does NOT show this gizmo. Alternately, page 14-10 is another drawing which does show the thing but does not identify it.

Reading elsewhere in the manual, it suggests 1 of three potential problems. 1) check valve in filter/regulator is bad - changed it already, so probably not it. 2) check valve in fuel pump is bad 3) leak in lines 4) leak in one or more injectors. Items 2,3 & 4 require testing pressure at the test port on the fuel rail - Snap on dude comes Tuesday mornings so I will get the correct adapter to fit my tester so I can do more tests.

Besides waiting on Snap On, anyone have an idea what the thing inside the red circle is?

Should have left the dang thing alone!

 

Filter did not cure problem. Also found that the first replacement filter was NOT a Wix, but a Mann. Second replacement is Mercedes.

Many of you knew this, but for those of us that did not the XFire filter is a combination fuel filter, fuel pressure regulator and has a check valve - all in that aluminum can. I just find it very odd that this problem occurred when the original filter was changed.

Going into this further, Photo 2375_LI is of my car with the new MB filter/regulator installed. Note red circle that has a metal canister installed inline with the fuel line going to the fuel rail. What is that? The second photo is a XFire fuel system schematic which does not show this thing. The third one shows the can but does not identify it. Looking at it, there is only a hose in and hose out with that dome shape can making me think there is some sort of diaphragm in it. Pressure pulse dampener??? Beyond that I got nothing.

Anyway, in the trouble shooting bit it says long cranking is likely due to a loss of pressure which can be for a variety of reasons, leaky injector, leaky check valve in pump, leaks in fuel lines or leaky check valve in fuel filter/regulator. so obvious next step is to check fuel pressure. For that I am waiting on Snap On truck this morning to get adapter for XFire fuel rail test port or will try the suggested a/c hose. A/C hose fits on rail but other end doesn't fit my tester so would have to modify it a bit.

Really hate it when I create problems for myself.

HP

 

A standard A/C hose screws on to the fuel rail, I used one for testing; when I designed my fuel pressure regulator system, fyi for testing. Woody

 

Well, I got the connector. Fuel pressure ramps up to 55 when key is cycled. Pressure stays at 55 with engine running. Drops to zero within 7 seconds of engine cut off. Clamped off supply to fuel rail. Pressure holds, so it should not be fuel rail.

Manual says slow drop off is check valve in pump. Fast drop off is check valve in filter. I presume seven seconds is fast? But I've changed filter twice - with MB unit on now. Not sure of what their definition of "fast" was so we went to clamping lines at filter. Clamped line at filter to fuel rail - pressure holds so it should not be any leaks in the fuel lines. Clamp on line to "Can" - no difference, pressure falls off. Clamp on line to "pump" - pressure holds. So, this indicates check valve in pump is bad? Said check valve choosing to fail just when the filter was changed?

Is my analysis above valid or am I missing something? Don't like coincidences. BTW, if I do get a new pump - is it Mercedes only or are there good reliable alternatives for less money?

HP

 

I did not think there was a check valve in the pump, why have two check valves in line?

 

Ya got me there - I'm only going by what is in the manual. However, reading the text, they appear to perform separate functions - as I understand it the filter check valve is part of the regulator assembly.

Right now I am trying to determine if the Bosch unit is equivalent to the MB - is it the original part supplier? The amazing interweb has a MB pump for about $500, a Bosch for $189 and some no name for $39. Heck of a range. Right now I am leaning toward the Bosch pump. In the mean time I am cycling the key to prime the system and reduce starter wear and tear.

HP

 

Personally, I think if the car runs OK after starting, the pump is fine.
I suspect the check valve in the filter to be the culprit, unless of course you have a leak somewhere between the filter and the fuel rail.

 

Rob @NeedsWings Performance Products sells an inline fuel line check valve complete w/ fittings sized for us for $79.95.

 

Look at the fuel pump on your car, it will have the Mercedes part number and the makers name and possibly their part number. My guess it is a Bosch part.

 

Sounds like a good idea except we've changed filter twice with no change and clamping fuel supply line system holds pressure. Also, clamped line feeding fuel rail at filter and pressure holds - so no fuel line issues. My guess is that the check valve leaks but the fuel pump can supply fuel to engine and make up for leakage. It does take about 7 seconds for the pressure to bleed off, so if it is the check valve it isn't stuck wide open but just leaking.

 

I was wrong all along, the pressure check valve is in the PUMP, not the FILTER.
Quote from manual :

 

Yep, that is indeed what it says about the fuel pump. But remember that the filter has FOUR outlets/inlets. Primary is in from pump and out to engine. Secondary are another return to tank and the joker is the outlet from the fuel filter/regulator valve itself - which also connects back o the tank - This is the small port labeled "can". If this valve sticks open it can bleed off pressure to the tank.

I would agree the primary check valve is in the pump.

All that said - no one has identified the metal can in my first photo. What the heck is that thing?

To quit beating a dead horse, I've bitten the proverbial bullet and ordered a Bosch pump from German Auto Parts in Charlotte NC. They are good folks I have dealt with in the past. Their store price is $145. Of course I shouldn't brag on them until I see if this does solve the base problem. Got the Bosch part number from onehundred80's reply - thanks! Still no clue as to why pump would fritz out when filter was changed.

One Plus side of the XFire is that the external pump design makes it much easier to change. of course I also think this is what caused all of my problems - whoever heard of a filter with four lines? Internal tank pumps are simultaneously simpler and more expensive

 

Going by the look of it it looks like a pressure regulator or a relief valve and my guess is it should not be there. Is it possible that the filter fitted has no pressure regulator in it so this was added. I have not had to study that area, so I am guessing.

 

All that said - no one has identified the metal can in my first photo. What the heck is that thing?


My best guess is that it is a little pulse dampener, for even fuel flow.

 

Yeah, I was guessing a pulse dampener also. As to "it shouldn't be there" I had to chuckle. I also agree with that, But it IS on the car and I sure didn't put it there, and it DOES show up on the schematic - Chrysler just chose not to identify it. A critique on the factory manual - they have all sorts of drawings with numbers all over them but NO legend as to what parts the numbers are calling out. Have to read the text to try and get a half way idea as to what is what because they don't reference all of the numbers in any text discussion. Is this a case of German engineering admitting that the thing has relative little value, so while it is there it cannot be tested so please just ignore it?

Also to clarify check valves in both the filter and pump, Volume 2 of 3, Page 14-4 of my 2005 OEM Shop manual at the bottom of the page has:

"Note: A quick loss of pressure usually indicates a defective check valve in the pressure regulator. A slow loss of pressure usually indicates a defective check valve in the fuel pump. These valves are not serviced separately if found defective, the entire component that the valve is part of much be replaced as an assembly."

Since the regulator is part of the filter, it seems that the filter indeed has a check valve.

 

I cannot see it on the schematic but it shows up in the sketch. It did not show up on my iPad, that is why I missed it, it shows up on my desktop though.

 

Regarding the manual stating that after 30 minutes it can bleed down to 36p.s.i., I believe this is a misnomer. It is my experience (and that of other x-fire owners)that the check valve can and does bleed down to a few p.s.i. after time. It only takes a pound or two of pressure to hold fuel in the lines from backing up. Even though my fuel rail gauge from Needswings shows zero after time, I know it has at least a couple pounds in there, as it always starts right up.
Even only one pound of pressure equals about 27 inches of water column;that is about the height difference between the pump and the injectors(give or take).